Changed Apple iD - now Messages not working
I changed my Apple iD yesterday.
Everything looked fine. (To confirm it had worked OK, I checked the details on https://appleid.apple.com/#!&page=signin.)
But now - after changing the iD - none of my old devices (iPhone, MBP and iPad) are receiving Messages. I’m only getting Messages on a brand new (2018 model) iPad that I set up yesterday.
Any idea of what’s gone wrong here, and how to fix it?
iPad (6th gen) WiFi